1. Field of the Invention
The present invention relates to an ink jet recording apparatus and, more particularly, to an ink jet recording apparatus in which a plurality of recording elements are divided into blocks and are driven at different timings every block.
2. Related Background Art
The ink jet recording method is a recording method whereby emission liquid droplets of a recording liquid (hereinafter, referred to as an ink) are formed by various methods and are adhered onto a recording medium such as a recording paper or the like, thereby recording.
Among recording apparatuses using the above recording method, an ink jet recording apparatus of the type which uses heat as an energy to form emission liquid droplets can be mentioned as an apparatus suitable to construct a recording head by arranging a number of emission ports at a high density.
In the ink jet recording apparatus using the heat as an energy to emit the liquid droplets, generally, by heating the ink, a displacement accompanied with a sudden increase in volume is given into the ink and ink droplets are emitted from the emission ports in association with such a displacement. For this purpose, the apparatus has a recording head comprising: an electrothermal converting element for generating heat and heating the ink; an ink liquid path which is communicated with the emission port and allows the heat generated by the electrothermal converting element to act on the ink; and the like. In the case of a recording head having a plurality of emission ports, a plurality of electrothermal converting elements and the like are also provided in correspondence to the emission ports.
The conventional ink jet recording head having such electrothermal converting elements, particularly, the ink jet recording head in which a plurality of electrothermal converting elements R.sub.1 to R.sub.mn are arranged in accordance with a plurality of emission ports corresponding to a recording width of one line as shown in FIG. 9, uses a structure such that the electrothermal converting elements are divided into a plurality of blocks (m blocks in FIG. 9) and the electrothermal converting elements are driven every block.
For example, in the case of driving the electrothermal converting elements at timings as shown in FIG. 10 in the circuit as shown in FIG. 9, a group of electrothermal converting elements corresponding to each of driving ICs comprising flip-flops 35.sub.1 to 35.sub.m, AND gates 36.sub.1 to 36.sub.m and 37.sub.1 to 37.sub.m, latch circuits 38.sub.1 to 38.sub.m, and shift registers 39.sub.1 to 39.sub.m are sequentially driven as one block, respectively.
Electric power consumption to drive the ink jet recording head by the above method is remarkably smaller than that of an apparatus which does not drive the electrothermal converting elements on a block unit basis, so that the above block driving method is used hitherto.
However, the above block driving method has the following problems because the electrothermal converting elements are driven every block.
A size of a common liquid chamber is limited depending on the structure of the head. To realize high-speed recording, it is a fundamental manner to reduce the driving time of each driving block as short as possible and to also reduce the driving time difference among the blocks as small as possible and to reduce the time which is required to form an image of one line. It has been found out from experiments that if an image is formed under the above conditions, a variation in concentration corresponding to the driving block occurs. Such a variation extremely deteriorates the image quality and is not practical.